Star Diary: 11 to 17 July

The full moon offers a great 'stargazing' opportunity this week, with asteroid Vesta also making an appearance.

BBC Sky at Night Magazine Star Diary podcast.
Published: July 10, 2022 at 8:00 am
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What's coming up in the northern hemisphere's night sky in the week of 11th to 17th July.



Ezzy Pearson Greetings listeners and welcome to Start Diary, a weekly guide to the best things to see in the Northern Hemisphere's Night Sky. In this episode, we'll be covering the coming week from the 11th to the 17th July. I'm Ezzy Pearson, the magazine's news editor. And I'm joined on the podcast today by reviews editor Paul Money. Hello, Paul.

Paul Money Now then, as a how are we doing?

Ezzy Pearson I'm doing well. But let us know what your recommendations are for the coming week's night Sky.

Paul Money Well, last week we did mention the moon. And when it's in the evening sky, it is the obvious object to actually observe. But on the 13th, it's full. Now, yes. Deep sky observers. Sorry, but the moon's full but it is light nights, so. So you're not exactly going to be seeing much in the way of deep sky. I always think Deep Sky is a case of what you call deep sky, Double stars. They don't need very dark skies sort of thing. So they're well worth looking at. And the moon doesn't need dark skies, does it? Sort of thing. And when it's full this is your chance to pick out a lot of the ray features. Now, we did mention that the Rays of Copernicus were beginning to appear last week as the Terminator was sweeping across Mare Imbrium and Copernicus hadn't quite appeared into the daylight on the moon's surface. Well, now it has. When we're full, we get a chance to see the Rays. Now a lot of people go for the most popular ones, and that has of course the typical Tycho, Copernicus, Kepler, Aristarchus. By the way, if you're Aristarchus, have a little side note sort of thing and look out for Schroter's Valley nearby. I mean, it's winding a ways. It's actually one of the most obvious valleys, I think more obvious really than Hadley Rille. Hadley really takes a little bit more observing skill to actually pick out. But Schroter's Valley definitely a lot easier, but there are a few others as well, and it's worth having a look out on the sky sort of thing to on the moon to actually see these and I always think Messier twin streaks, so I mean, messier isn't deep sky objects alone. There is a crater Messier actually on the moon as well in mare Fecunditatis. So have a look at the two... It's very strange because it's the only one I know that's got twin streaks coming out of it, so there are others as well because I say the obvious ones, we always go for them. But there's Menelaus. There's some streaks coming out from that and Aristillus as well. So, you know, there are other subtle ray features, but they take a little bit more careful observation, working out where they are and then following those streaks. There's several streaks over Oceanus Procellarum as well, and they're coming from a crater. I'm not sure which crater I have to say because it's on the lunar limb. Very difficult to see which crater it is. But so perhaps our listeners would like to pop in. Even I readers, sort of thing, when they get the magazine, might want to comment on that and see if they've seen these faint rays crossing Oceanus Procellarum from the right on the limb. So I'd like to know which one it is. I'm not a big lunar observer, so that's something. I've only spotted them a few times, so I've never really paid a lot of attention. But somebody thought, why not have a look? I can do something different out of your normal routine sort of thing. So this is the time to do it. This is when the ray features are really at their best. I would say don't just stick to the main obvious one. There are a few others as well. When we get to July the 16th, now the moon, this is the interesting thing is the moon is below Saturn. Yes, Saturn is in the evening sky now. It's actually rising around about 11:00 ish. In fact, just before 11:00. So by midnight on the 16th, it's actually a well above the horizon. It finds it almost above due south east. So we've got in actual fact, Saturn. But Saturn also formed a bit of a triangle with two of the stars in Capricornus. So it's above delta Capricorni and forming a triangle with Gamma Capricorni as well, which is just to the right of them. So you've got this lovely little triangle of Saturn and these two other stars and then hanging below them, we've actually got the moon as well sort of thing. So this is the 16th, so around about two or three days after full moon to look over towards the east as well. Because if you got Saturn and the moon at about midnight, incredibly, Jupiter is just rising. Now we haven't yet reached oppositions. We're going to get to them later on in the year. But it just shows you that they are becoming better placed to observe and that it won't be long before they're even the evening sky. A lot easier to observe. And to be fair, more people will look out for them. Because let's face it, when things are in the evening sky and especially the early evening skies you get towards the end of the year, then a lot more people tend to notice these planets and the moon, etc. So these are for the dedicated astronomer. Those of us who like to get will stay up late and observe these things. So ironically, the minor world Vesta is also up because it's in Aquarius as well. So we've got a few of the planets that we usually class in the morning parade. They are now beginning to creep into the evening sky, but late evening sky. So just before midnight. Now, I mentioned Vesta because on July 17th and we're looking around about ironically 17 minutes past midnight. So on the 17th, there we are. So Vesta is now easier to spot and it is actually around about magnitude 7.4. So, you know, it's well worth having a go at Vesta because binoculars will actually show it. But the moon is nearby on the 17th, in fact its to the left of Vesta. But there's a bit more to it, because as the moon rises, this is why I mention it, at 17 minutes past midnight on the 17th, the moon will be well up and you'll see a star to the right. We'll start earlier. Keep a lookout on the horizon and watch the moon rise because the moon is occulting this star and this star is Tau Aquarius. So it's being occulted. So we don't see the start, which would have been on the bright limb anyway, is always a lot harder to view that, but it's always easier to see the sudden reappearance of the star. And it can be quite startling because one minute you've got this dark limb, you can just probably see a little bit, probably not a gibbous moon. So there's very little earthshine, but with a telescope you might get a hint of something, but it's basically the dark side. And then suddenly this dot light appears on the edge. And is that instantaneous? Because the stars are pinpoints of light to us. Unless they're doubles, it has some doubles were discovered Ezzy, whereby an the occultation took place. Suddenly one saw a bit and then the next. And they suddenly rise. It wasn't a single event. There was actually two. So there is Tau Aquarii appearing from behind the Moon and to the left of Vesta, so you can use Tau as a guide to Vesta itself, and so can find a minor planet, you've got the moon, the two solar system objects and of course a star, which is an Aquarius as well. So there we are by 17 minutes past midnight. It will definitely be visible that star. But keep watching from when it rises. The moon rises and you'll see the reappearance of Tau Aquarii. So I always love these this sudden apparent sort of thing, these stars. And they, you know, that they can be quite startling, to be fair, you know, because it is such an abruptness to it. But you've got this dark space. And then suddenly 'bing' there is it's in view. The only time it's different is when it's greys in the north or southern horizon of the moon, you get a graze in occultation. And then I've only seen a couple because its usually cloudy with the rest. Wherever these events are happening its cloudy isn't it? But hopefully we have clear skies. But it's quite something to see the star flit in and out, pruning the valleys of the moon brace as you get this star flickering and what you're really seeing is the mountains. The moon's getting in the way and block it, occulting the star briefly. But that won't happen this time. But yeah, there are various occultations and great occultations throughout the year because the moon course goes around the whole of the earth and a month and throughout the year, you know, we see a whole range of different stars nearby to the moon and some occulted as well. So there we'll finish the week with an occultation, but the reappearance of Tau Aquarian.

Ezzy Pearson That does sound like a particularly striking event to end this week on. So thank you very much for taking the time today, Paul, to tell us all about what we can see this week on the night sky.

Paul Money My pleasure.

Ezzy Pearson If you want to find out even more spectacular sites that will be gracing the night sky throughout the month. Be sure to pick up a copy of BBC Sky at Night Magazine. Well, we have a 16 page Pullout Sky Guide with a full overview of everything worth looking out for. Whether you like to look at the moon, the planets, or the deep sky, whether you use binoculars, telescopes or neither, our Sky Guide has got you covered with the detailed star charts to help you track your way across the night sky. From all of us here at BBC Sky and Night Magazine goodbye.


Chris Bramley Thank you for listening to this episode of The Start, our podcast from the makers of BBC Sky Night magazine. For more of our podcasts, visit our website at or head to ACast, iTunes or Spotify.


Elizabeth Pearson
Ezzy PearsonScience journalist

Ezzy Pearson is the Features Editor of BBC Sky at Night Magazine. Her first book about the history of robotic planetary landers is out now from The History Press.


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